Reactors which are inductance parts including a core having a built-in coil configured of a wound electric wire have conventionally been used in various fields.
For example, in hybrid vehicles, fuel cell vehicles, electric vehicles, or the like, a booster circuit has been disposed between the battery and the inverter which supplies alternating current power to a motor (electric motor), and a reactor (choke coil) which is an inductance part is used in the booster circuit.
In hybrid vehicles, for example, the battery has a voltage of about 300 V at the most, while it is necessary to apply a high voltage of about 600 V to the motor so as to obtain high output. A reactor is used as a part for the booster circuit for that purpose.
Such reactors are in extensive use in booster circuits for photovoltaic power generation and in other applications.
The reactor in operation generates heat and, due to the heat generation, the internal temperature of the core undesirably reaches a high temperature. In some cases, the inner part of the core partly heats up to a temperature higher than a set permissible maximum temperature.
For example, reactors for use in the booster circuits of vehicles are parts that are used over an exceedingly long period, and in the case where temperature rising is repeated for a long period, the resin binder deteriorates due to the heat history, resulting in a decrease in the life of the parts.
Consequently, a temperature permitted to be reached (maximum temperature) is set for reactors, and the temperature rising due to internal heat generation is required not to result in a temperature higher than the set maximum temperature.
As a prior-art technique relevant to the present invention, the following patent document 1 discloses a feature wherein, since a reactor including a coil covered with a core has a problem in that the internal temperature of the vicinity of the coil is apt to rise, a heat sink piece which is constituted of a rod member made of aluminum and which is for dissipating the heat from the coil to the outer case has been disposed in the core.
It is, however, noted that the reactor disclosed in patent document 1 differs from the present invention in means for heat dissipation.
Meanwhile, patent document 2 shows an invention relating to a “reactor”, and discloses a feature wherein an electrically non-conductive filler is added to a mixture of a soft magnetic powder and a resin to regulate the viscosity of the mixture and a feature wherein the heat dissipation properties of the soft-magnetic composite material can be improved in cases when a material having a high thermal conductivity, such as, in particular, Al2O3, BN, or AlN, is used as the filler.
However, patent document 2 does not disclose a feature wherein fibrous filler is used as the filler having a high thermal conductivity, and differs from the present invention in this respect.